Normal Pregnancy

The Third Trimester of Your Pregnancy

The third trimester of your pregnancy spans from week 26 to the birth of your baby. Although your due date marks the end of your 40th week, a full-term pregnancy can deliver between the 37th and 42nd weeks of pregnancy. During this final trimester, your baby grows larger and the body organs mature. The baby moves frequently, especially between the 27th and 32nd weeks.

At the end of the third trimester, your baby will most often settle into a head-down position in your uterus, preparing for birth. This position will likely cause you some discomfort as you get close to delivery.

What You May Feel

Your third trimester is a time of rapid weight gain for your baby. The baby's increasing size and the many changes your body goes through to prepare for labor and delivery may cause the following to occur.

  • Feeling the baby's movements strongly.
  • Shortness of breath because the top of your uterus now rests under your rib cage.
  • Need to urinate more often as the baby drops and puts more pressure on your bladder.
  • Colostrum (a yellow, watery pre-milk) may leak from your nipples.
  • Navel sticking out.
  • You may have contractions. These can signal false labor or real labor.
Prior to pregnancy, your uterus weighed two ounces and was capable of holding half an ounce of liquid. By the time you deliver, it will weigh over two pounds and hold a quart of amniotic fluid.

When To Call The Doctor

Many physical changes occur during your third trimester. While most of these changes are to be expected, you should call your doctor if you experience any of the following symptoms.

  • Heavy vaginal bleeding or clotting
  • Lighter bleeding that lasts for more than one day
  • Any amount of bleeding that is accompanied by pain, fever, chills, or severe abdominal or shoulder pain
  • A severe or persistent headache, particularly one that is accompanied by dizziness, faintness, or visual disturbances
  • Dehydration
    • By the start of the third trimester, your uterus is large and hard, your baby's movements are visible, and you may be experiencing false labor.
  • A fever of more than 101°F
  • Painful urination
  • A watery discharge from the vagina
  • Sudden swelling of the face, hands, or feet
  • The signs of premature labor: regular uterine contractions, lower back pain, a feeling of heaviness in the lower pelvis or abdomen, diarrhea, slight spotting or bleeding, or a watery fluid or mucus discharge
  • A significant decrease in fetal movement after the 24th week of pregnancy.

Screening Tests

Women with group B strep bacteria may experience no complications at all or develop bladder, uterine, or other infections.

The American Academy of Pediatrics recommends that all pregnant women be screened for group B strep bacteria between 35 and 37 weeks of pregnancy. This type of bacteria is carried by 10% to 30% of pregnant women and is found most often in the vagina and the rectum. Your doctor will talk with you about the risks this bacteria poses to you and your baby and how to prevent them.

Because you can pass the group B strep bacteria to your baby during pregnancy, delivery, or after birth and a baby infected with group B strep may end up with blood, lung, brain, and spinal-cord infections, it is especially important to be screened for this type of bacteria.

The group B strep test involves taking a culture from your vagina, perineum, and rectum during pregnancy. The results of the culture are available within two days. If your test comes back positive, your doctor will recommend that you take antibiotics during your labor to minimize the risk of passing group B strep to your baby.

How Your Baby Grows

Your baby continues to gain about 1% of its weight each day during the third trimester of pregnancy. Males tend to be slightly heavier than females.

During your third trimester, your baby will more than double in size. In fact, by the ninth month, your baby may be gaining more than a half-pound per week.

Here's what your baby is doing during the seventh month of your pregnancy:

  • Eyes can open and close and sense changes in light.
  • Kicks and stretches.
  • Grasping motions and response to sound.
  • By the end of this month, your baby will be 14 inches long and weigh between 2 and 2 1/2 pounds.

At the end of the eighth month, your baby is 18 inches long and weighs approximately 5 pounds. Other developments include:

  • Your baby is gaining weight very quickly.
  • Bones harden, but the skull remains soft and flexible for the delivery.
  • The different regions of the brain are forming.
  • Taste buds develop and the baby can now taste sweet and sour.
  • Your baby may now hiccup.

Here's what your baby is doing the ninth and final month of your pregnancy:

Although you might feel a little odd interviewing caregivers for your baby before he or she arrives, this is one task that needs to be handled before the birth
  • Your baby usually turns into a heads-down position for birth.
  • The skin is less wrinkled.
  • The lungs mature and are ready to function on their own.
  • Sleeping patterns develop.
  • Your baby will gain about a 1/2 pound per week.
  • By the end of your pregnancy, your baby will be approximately 20 inches long and weigh between 6 and 9 pounds.